Method of treating cold-rolled metals



July 11, 1939. (1 E Y 2,165,635

METHOD OF TREATING COLD-ROLLED METALS Filed Oct. 27, 1957 [madma- Patented July 11, 1939 UNITED STATES PATENT, OFFICE a sacss METHOD OF TREATING COLD-ROLLED METALS 1 Claim.

This invention relates to cold-rolled metals, and particularly to a method of treating the surfaces thereof.

During the annealing of sheet or strip metal there is a tendency for the adjacent coils or sheets of the material to stick together which is, of course, very undesirable. These sticking surfaces, therefore, have to be separated in some manner after the metal is annealed. Various means have been employed to prevent the contacting surfaces from sticking together, but none of them have been very successful. Generally, the means employed is an oil, or a mixture or lubricant including an oil, which is applied to the surfaces of the metal during the final rolling to act as a separating medium. Usually the means employed left an ash or an undesirable residue 'on' the metal which tended to pit the surface venting the contacting surfaces of strip or sheet metal from sticking together.

Various other objects and advantages of my invention will more fully appear in the course of the following specification, and will be particularly pointed out in'the appended claim.

In the accompanying drawing, I have shown, for the purpose of illustration, one embodiment which my invention may assume in practice.

In the drawing:

Figure 1 is a schematic view'showingthe application of my invention in connection with a fourhigh reversing mill stand; and,

Figure 2 is a sectional view taken on the line 11-11 of Figure 1.

There is shown in the drawing a final pass cold-reduction mill apparatus ofthe reversing type comprising working rolls 3 and I, an entry reel 5, a delivery reel B and guide-rolls I and 8. A coil of metal is placed on the reel 5 and the strip metal 9 passes over the guide-roll I between the cold-reducing working rolls 3 and 4 for the final pass and then over theguide-roll 8 onto the delivery reel 6. As the strip of metal passes between the working rolls 3 and 4 heat is, of course, generated, which generally raises the temperature of the metal to about 250 degrees Fahrenheit, which is, of course, above the boiling point of water.

' According to this invention, there is provided a low-pressure stream of either hot or cold water which is preferably applied to the center of the strip by means of a conventional adjustable nozzle II and water supply hos'e II, or by any other 10 suitable means. The water is applied preferably just before the metal is coiled, as shown. As the water comes in contact with the heated surface of the strip metal 9 the water is, of course,

rapidly heated to the point where a portion there- 5 of is converted into steam. Due to the fact that the chemical and molecular activity of the metal strip is increased as its temperature is raised, a rapid reaction is developed between the metal strip and the oxygen in the water, the water vapor and the surrounding air, which results in the formation of an oxide on the surface of the metal strip,

For example, in cold rolling ferrous metals, and particularly, strip steel having-a low carbon content as used for deep drawing processes and the like, the temperature of the metal as it leaves the mill is governed by the amount of reduction 'of the metal in rolling and the type and amount of lubricant used. Usually the temperature of such metal as, it leaves the mill is between 200 and 300 degrees Fahrenheit, but it is sometimes lower and sometimes higher than this. Of course, a thinner coat of oxide will be formed on the surface of the metal at lower temperatures than at higher temperatures. However, it has been found that an uneven coating of oxide is formed on the surface of the metal by the water when the temperature of the metal is below approximately 150 degrees Fahrenheit. This is probably due to the 40 fact that the metal strip is quite oily as it leaves the mill, thus tending to puddle or accumulate the water in spots below this temperature. Therefore, it is important that such strip metal be at a. temperature above approximately de grees Fahrenheit at the time the water is sprayed thereon. I

As the metal strip passes beyond the point of application of the water, onto the delivery reel, the tension of the coiled strip causes the excess water to be squeezed from between the adjacent convolutions of the coil. After the metal is coiled, it is usually sheared to the desired lengths and the sheared sheets stacked and charged for box annealing. During the annealing operation the thereby. This coating of oxide seems to disappear during the annealing operations.

As a result of my invention, it will be'noted that I have provided a means for preventing contacting surfaces of cold-rolled material from sticking together by a simple and inexpensive method which is, at the same time, both effective and eflicient.

While I have in this application specifically described and shown an embodiment of my invention, it will be understood that this embodiment is merely for the purpose of illustration and description, and that various, other forms may be devised within the scope of the invention,

as defined in the appended claim.

I claim:

In the manufacture of cold-rolled strip ferrous metal, the method of treating the strip which comprises passing the strip through the final pass cold-reduction mill wherein the temperature of the metal is raised and delivered therefrom at a temperature of at least 150 degrees Fahrenheit, immediately applying an aqueous solution consisting solely of water to at least one surface of said strip at said temperature whereby the oxygen in said water reacts chemically with the metal to form a relatively thin and even coating of iron oxide on the surface thereof, and tightly coiling said strip immediately thereafter so as to cause the excess water to be squeezed from between the convolutions of the coil and be removed from said surface, said oxide coating adapted to serve as a separating medium between the adjacent metal surfaces so as to prevent said surfaces from adhering to each other during the subsequent annealing of the metal.

JAMES 0. KEIGHLEY. 

